Hi,
I'll try to explain:
1. You need Crowtrobot's Custom Liveries Tool, which can be found
here on the official forum.
2. Create a proper file/folder structure for the liveries you want to install. Make on folder per car (here:
Mercedes C Coupe DTM), which contains one folder per custom livery (here:
2012 DHL Paket Coulthard #19; this will also be the name of the livery in-game):
I recommend to store these folders somewhere else but in your pCars folder, that would be quite confusing.
3. Open the Custom Liveries Tool, select the vehicle in the list on the left and hit the Load button above. The window to select the directory will open. Go to your storage folder (in my case
Custom Liveries), select the car folder (double click it, the folder will open, but do not select anything inside of this new opened folder) and confirm your choice (
Ordner auswählen).
4. You'll see something similiar like this (maybe less entries) in the main window. Select the liveries you want to bring in-game and hit the
>> button.
5. The entries will now be in the Livery List on the right. Hit the
Assign Liveries button, the tool may need a few seconds (copying the files into Vehicles/Textures folder, backing up the old rcf-files, creating new ones,...). When it's finished you can read the line
Liveries added to: ... at the bottom of the tool window.
6. You should now be able to select the liveries you just added in game.